1. Field of the Invention
The present application is generally directed to a system and method for generating a terrain representation. More specifically, the present application is generally directed to a system and method for generating a terrain representation that, in one arrangement, utilizes at least a plurality of dynamic color bands, each band representing a certain band or level of terrain elevation. In this manner, either a static or dynamic visual map may be provided of a terrain over which a vehicle is passing, such as an aircraft. However, aspects of the invention may be equally applicable in other scenarios as well.
2. Description of Related Art
In the navigation of an aircraft or other type of vehicle (land, water, air, etc.) traveling over some type of planned route, such as an air route, contour or terrain maps are typically relied upon to represent terrain configurations over which the vehicle passes. Ordinarily, a pilot or perhaps some other crew member of the aircraft utilizes certain data provided by such contour maps in conjunction with instrument readings and/or visual observations of the terrain. Such contour maps and associated geographical data may be used in determining an altitude and/or course of the vehicle or aircraft as the vehicle or aircraft passes from point to point along such a planned or designated planned route.
Methods and systems for generating terrain representations are generally known. Certain known methods and systems for generating terrain representations ordinarily utilize a large number of colors to represent differing terrain elevations. For example, in certain systems that are utilized to represent absolute terrain height of planet earth oftentimes utilize a total of up to thirty-two (32) different colors. Using such systems that rely on a large number of different colors oftentimes present certain complications.
As just one illustration, when using such a large number of colors to represent absolute height of a certain terrain (such as planet earth), elevation differences may tend to be artificially accentuated when there is a hue shift in displayed colors. In other words, there could be a deminimus elevation difference of perhaps one thousand feet that may be represented by a hue shift in color as the colors are displayed. Such known methods and systems may utilize two different hues to represent a mere difference of one thousand feet in elevation in one case. In another case, such known methods and systems may use only one hue (with saturation and luminance differences) to represent the same altitude variation. For instance, in the situation where 30,000 feet of elevation is represented by 32 colors, the lower 16 of these colors use a green hue, plus a change in saturation and luminance to differentiate among colors and add gradient to the terrain visualization. The higher 16 of these colors use a brown hue, plus a change in saturation and luminance to differentiate among colors and add gradient to the terrain visualization. At the midpoint of the elevations represented, i.e., 15,000 feet, the hue shifts from green to brown.
Consider, in one instance, where an aircraft is flying at 7,000 feet, with the highest altitude in display view at 7,500 feet, and the lowest altitude in display view at 6,500 feet. In the case where two colors are being used to characterize the 1,000 feet in altitude variation, both colors would be within a green hue. The difference in elevations will be portrayed using a change in saturation and luminance, while the hue largely remains the same, i.e., that is, the hue remains green. Now in the situation where an aircraft is flying at 15,000 feet, assume that the highest altitude in display view will be at 15,500 feet and the lowest altitude in display view will be at 14,500 feet. Again, if two colors are being used to characterize the 1,000 feet in altitude variation, but now because the altitudes displayed are at the point where the hue shift (from green to brown) occurs, the 1,000 feet of altitude variation in the second case will be portrayed with a greater degree of emphasis (green to brown shift) than the 1,000 feet of altitude variation in the first case (green hue only). Because there are many altitudes to represent and differentiate, it is frequently the case that the green and brown hues are used, and consequently, where the split between the hues occurs, the altitude variation may tend to be over-emphasized.
Another concern that can often arise with certain known systems having a large number of different hues is that such systems tend to raise the possibility of conflicting colors when new data sets are overlain on the terrain colors. For instance, if hues in addition to green and brown are used (perhaps in an attempt to evenly distribute more hue shifts across the terrain elevations), the new colors selected for the background terrain can easily conflict with critical foreground symbology. For instance, magenta, red, yellow, and cyan already have meanings associated with foreground symbology in aircrafts. As such, as colors in the background terrain approach the colors in the foreground symbology, important elements of the foreground symbology may blend with the background and become hidden or confusing to interpret.
There is, therefore, a general need for a system and/or method that minimizes the number of different colors or hues that may be used for certain terrain representations, such as a representation of the earth's terrain. There is also a general need for a system and method of generating terrain representations that does not generate representations that are artificially accentuated when there is a hue shift in color.
There is also a general need for a system and method of generating terrain representations that does not create conflicting colors when new data sets are overlain on the terrain colors. That is, there is a need for a system and method that utilizes background colors that are not similar to foreground colors. Because a good number of foreground colors are already in use, the hues available for background colors should be limited. At the same time, there is a need to fully represent the absolute altitude variations in the field of view of a display.
In a current generation of an Enhanced Ground Proximity Warning System, a “Peaks” mode exists to portray absolute terrain. However, the “Peaks” mode does not necessarily show all terrain, but rather represents the high terrain in several bands when the aircraft is at a cruise altitude. A method that represents all absolute terrain in the zoom view of the map, while at the same time using a minimum amount of colors for that full representation, and consequently allowing easy integration of colors from other map layers (for instance, relative terrain to the aircraft shown as green, yellow, and red bands), would provide certain advantages for situational awareness and system usability.
Minimizing the use of color may also be advantageous for preserving the meaning of the color, reducing color conflicts among data sets, as well as creating a simpler display overall. It would be useful to develop a terrain coloration model that minimizes the use of color while giving a member of a flight crew (e.g., a pilot) adequate resolution between terrains of different heights. Ideally, the color model should present finer terrain color resolution when zoomed in (i.e., when viewing details), and coarser terrain color resolution when zoomed out (i.e., when viewing an overall picture).